National Instruments Welding System 321645c-01 Manual De Usuario
Chapter 2
Function Reference — DAQ_Start
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National Instruments Corporation
2-137
NI-DAQ FRM for PC Compatibles
buffer is an integer array. buffer must have a length equal to or greater than count. The
elements of buffer are the results of each A/D conversion in the DAQ operation. This buffer
is often referred to as the acquisition buffer (or circular buffer when double-buffered mode is
enabled) elsewhere in this manual.
elements of buffer are the results of each A/D conversion in the DAQ operation. This buffer
is often referred to as the acquisition buffer (or circular buffer when double-buffered mode is
enabled) elsewhere in this manual.
For DSA devices, buffer should be an array of i32. These devices return the data in a 32-bit
format in which the data bits are in the most significant bits.
format in which the data bits are in the most significant bits.
count is the number of samples to be acquired (that is, the number of A/D conversions to be
performed). For double-buffered acquisitions, count must be even.
performed). For double-buffered acquisitions, count must be even.
Range:
3 through 2
32
– 1 (except Lab and 1200 Series devices that are not enabled for
doubled-buffered mode and the E Series devices)
3 through 65,535 (Lab and 1200 Series devices not enabled for double-buffered
mode).
2 through 2
3 through 65,535 (Lab and 1200 Series devices not enabled for double-buffered
mode).
2 through 2
24
(E Series devices).
2 through 2
24
– 3 (PCI-6110E and PCI-6111E). count must always be EVEN.
2 through 2
24
(PCI-445X).
2 through 2
32
– 1 (PCI-455X).
timebase is the timebase, or resolution, to be used for the sample-interval counter. timebase
has the following possible values:
has the following possible values:
–3:
20 MHz clock used as a timebase (50 ns) (E Series only).
–1:
5 MHz clock used as timebase (200 ns resolution) (AT-MIO-16F-5,
AT-MIO-64F-5, and AT-MIO-16X only).
AT-MIO-64F-5, and AT-MIO-16X only).
0:
External clock used as timebase (connect your own timebase frequency to the
internal sample-interval counter via the SOURCE5 input for MIO boards or, by
default, the PFI8 input for E Series devices).
internal sample-interval counter via the SOURCE5 input for MIO boards or, by
default, the PFI8 input for E Series devices).
1:
1 MHz clock used as timebase (1 µs resolution) (non-E Series MIO devices only).
2:
100 kHz clock used as timebase (10 µs resolution).
3:
10 kHz clock used as timebase (100 µs resolution) (non-E Series MIO devices
only).
only).
4:
1 kHz clock used as timebase (1 ms resolution) (non-E Series MIO devices only).
5:
100 Hz clock used as timebase (10 ms resolution) (non-E Series MIO devices
only).
only).
On E Series devices, if you use this function with the timebase set at 0, you must call
the function
the function
Select_Signal
with signal set to
ND_IN_CHANNEL_CLOCK_TIMEBASE
, and
source set to a value other than
ND_INTERNAL_20_MHZ
and
ND_INTERNAL_100_KHZ
before
calling
DAQ_Start
with timebase set to 0; otherwise,
DAQ_Start
will select low-to-high
transitions on the PFI 8 I/O connector pin as your external timebase.
Refer to the
Select_Signal
function for further details about using the timebase with
E Series devices.